Additive manufacturing and numerical modeling polymer stents

Biodegradable stents are one of the promising trends in cardiology with a number of advantages over metal stents. Studies show that these stents can effectively restore the vessel lumen and at the same time dissolve organically in the body tissues, minimizing the risk of complications. The production of biodegradable stents by FDM-printing allows to diversify the types of fabricated structures and is also an economically advantageous solution. Numerical modeling of the expansion process of 6 stent geometries was performed. A biodegradable polymer, polylactide (PLA), was used as the stent material. The maximum expansion at the ends was achieved by stent no. 2 with five-element struts. However, in the central region, the best expansion is obtained by stent no. 4 consisting of nine-element struts. The minimum and maximum stresses of the structures are 77.1 and 83.1 MPa, respectively. In all stents after unloading, the transition to the zone of plastic deformations in the crown and link regions was revealed (max = 0.65, min = 0.1). Based on the modeling results, the coefficients of radial elasticity, shortening and unevenness of stent opening were calculated. A comparative analysis of the influence of the stent wall thickness on its ability to expand and maintain its stress-strain state was also performed, which showed that stents with 0.4 mm thickness, in contrast to 0.2 mm thickness, expand better and retain a significant opening after the load is removed from the stent.